Officials intentionally released and burned off toxic vinyl chloride from five ... and they executed the vent and burn. NTSB officials have said an overheated bearing on one of the railcars ...

the harshest criticism focused on the railroad’s advocating for a controlled explosion and burn of five tank cars full of vinyl chloride, a toxic chemical three days after the derailment.

Jennifer Homendy, chair of the NTSB, opened the hearing ... was described as a "vent and burn" procedure on the tank cars containing vinyl chloride, sending a toxic plume of smoke into the air ...

Tuesday’s meeting — where the NTSB approved the findings of ... In a report last week, researchers found that the toxic chemicals released in the burn spread over 16 states, reaching as ...